Comments
1

I am fully convinced that optical control of the interface between therapy head and the patient’s body is of great value. With this method bubbles can be identified and removed by sweeping the hand over the surface of the therapy head (top of the water cushion).

It is not mentioned in how many cases that air-bubbles were identified and the sweeping action necessary if the patient (similar to the situation in Group 1) was just lowered towards the water cushion. The extended question is what we can learn from this experience? Is there a standard hand-sweeping procedure that, properly applied, might eliminate air-bubbles blindly? That would be a useful lesson to learn for all those SWL-operators who do not have access to this optical device?

The authors mention some additional factors of great importance for success:

1. To use ultrasound gel with low viscosity.
2. Gentle application of large volumes of bubble-free gel.

I am fully convinced that optical control of the interface between therapy head and the patient’s body is of great value. With this method bubbles can be identified and removed by sweeping the hand over the surface of the therapy head (top of the water cushion).
It is not mentioned in how many cases that air-bubbles were identified and the sweeping action necessary if the patient (similar to the situation in Group 1) was just lowered towards the water cushion. The extended question is what we can learn from this experience? Is there a standard hand-sweeping procedure that, properly applied, might eliminate air-bubbles blindly? That would be a useful lesson to learn for all those SWL-operators who do not have access to this optical device?
The authors mention some additional factors of great importance for success:
1. To use ultrasound gel with low viscosity.
2. Gentle application of large volumes of bubble-free gel.